Most politicians I like disappoint me sooner or later. The last year or so, John McCain has joined their ranks. Some of the reasons why (and why the man will have a hard time becoming president) are summarized in this article by E.J. Dionne.
While you're at it, read this weblog post about how McCain, who once denounced Jerry Falwell as a bigot, is now his bosom buddy. I don't think Falwell is the one who's changed.